The state has more than 4,000 untested kits, according to Tofte's estimates.

The law specifically mandates that DNA evidence collected in criminal sexual cases to be sent to the Illinois State Police crime lab within 10 days of gathering it, starting October 1. Technicians must finish analyzing the samples within six months only "if sufficient staffing and resources are available."

Law enforcement officials admitted to the Chicago Tribune they sometimes were uncertain if the DNA evidence collected in some instances could be legally examined or help with their investigations.

Victims' advocates are praising the new law's protections for victims and the promise of future arrests and prosecutions of sexual assault suspects.

"We believe that more undetected serial rapists will be identified among that population of men who are already coming to the attention of the criminal system, thanks to the brave reports of girls and women who come forward even when they know that they will be disbelieved," said Kaethe Morris Hoffer, a director of the Chicago Alliance Against Sexual Exploitation.